1. Field of the Invention
This invention relates to a tape cassette, and more particularly to an improvement in a tape cassette of the type in which a magnetic tape wound on and guided between supply and take-up reels is withdrawn from the front opening of the cassette housing in use, and a flexible strip affixed to the cassette housing biases against the magnetic tape to prevent it from moving when the cassette is not in use.
2. Description of the Prior Art
Conventionally, a tape cassette used in a video tape recorder (VTR) is installed into an operative position in the VTR, and the magnetic tape in the cassette housing is engaged with a loading mechanism of the VTR. The magnetic tape is withdrawn from the front opening of the cassette housing by the loading mechanism so that the tape is threaded along a predetermined path. The magnetic tape is run in the loaded condition to record signals thereon or to reproduce signals therefrom.
In the tape cassette, the ends of the magnetic tape are respectively affixed to supply and take-up reels mounted in the cassette housing. A length of the magnetic tape between those portions wound on the supply and take-up reels extends across the front opening of the cassette housing, when the tape cassette is not in use, that is before the magnetic tape is withdrawn from the front opening of the cassette housing. Since the supply and take-up reels are freely rotatable in the cassette housing, the magnetic tape is easily made loose or slack by vibration or shock during handling of the tape cassette. Such looseness and slack bring about various disadvantages, and can lead to damage of the slackened portions of the magnetic tape. Then the tape cassette with damaged tape is installed in the VTR, troubles are apt to occur in the operation of the VTR. Furthermore, the slack in the magnetic tape may lead to defective recording or reproducing operations.
Accordingly, a member for avoiding such slack or looseness of the magnetic tape when not in use is employed in a prior art cassette-type VTR or tape recorder. For example, it is disclosed in the U.S. Pat. No. 3,797,779 and No. 3,802,648 having the same assignee as this application. In the foregoing Patents, the member for avoiding the slack or looseness of the magnetic tape comprises a flexible film strip affixed at one end with adhesive to a part of the lower half of the cassette housing. The other, free end thereof has a layer of low friction material such as soft synthetic resin. The magnetic tape is pressed between the free end of the flexible film strip and another part of the lower half of the cassette housing, so that it is prevented from slackening or loosening when the tape cassette is subjected to vibration or shock.
However, since the flexible film strip is affixed to the cassette housing with adhesive, the number of steps required for assembly is rather high, and the manufacturing efficiency is low, resulting in high cost. Further, as adhesive deteriorates with age, the adhesive can eventually give way, and the flexible film strip can fall from the cassette housing. Further, the construction of a conventional cassette makes it very difficult to automatically mount the flexible film strip onto the cassette housing.
Alternatively, methods for mechanically fixing the flexible film strip to the cassette housing have been proposed. In one example, the flexible film strip is mounted on the lower half of the cassette housing, and then the upper half of the cassette housing is mated with the lower half of the cassette housing, so that a projection formed on the upper half of the cassette housing holds the flexible film strip. However, if the lower half of the cassette housing is subjected to vibration during the mating operation thereof with the upper half, or if another part, while assembled, contacts with the flexible film strip mounted on the lower half, the position of the flexible film strip can accidentally vary. Accordingly, much care should be taken in the assembling operation, with the result that the manufacturing efficiency is reduced. Also, if the upper half is mated with the lower half, when the position of the flexible film strip is deflected, the film strip can be damaged.
In some manufacturing techniques, the upper half is mated with the lower half before the magnetic tape is assembled in the tape cassette and the empty tape cassette is transported from one manufacturing facility to another for the final manufacture of the tape cassettes. In the other facility, the upper half is separated from the lower half in order to assemble the magnetic tape. In the separating operation, there is a possibility that the flexible film strip can become demounted from the lower half when with the upper half is separated.